Transcript biometry
Biometry Measurements 1) Tree Canopy Cover Percentage (trees are 5 m or more in height) pace semi-diagonals (using densiometer) 2) Shrub Cover Percentage (shrubs are under 5m in height) pace semi-diagonals (using densiometer) 3) Identification of Dominant and Co-Dominant Species pace semi-diagonals (using densiometer and plant guide(s)) 4) Tree Heights of Dominant Species and Co-Dominant Species trigonometric relationships (using clinometer and tape measure) 5) Tree Circumferences of Dominant Species and CoDominant Species measure at 1.35 m (using tape measure) 6) Grass Cover 7) Grass Biomass When to make Biometry measurements Each year, make your biometry measurements – once near the peak of the growing season when maximum green leaves or grass are present – once during the least active season if you have one (i.e. when broad leaf trees have lost their leaves in temperate regions). Determining Pace ‘Pace’ is a very convenient measurement of distance that everyone can use - no need to take along a meter tape A pace is 2 steps To find you pace – – – – – stretch out a 50 m tape flat on the ground start with heel or toe on 0 m, then walk 10 normal paces note where heel or toe lands on 10th pace [say 15.7 m] divide by 10 to get average pace [gives 1.57 m] repeat twice more; average all 3 results Alternatively can measure how many paces it takes to walk 21.2 m (take three replicates and average) Biometry Measurements Land Cover Sample Site (homogenous land cover) Homogeneous Land Cover N LANDCOVER = ________________ 30 m GPS 90 m 90 m 90 m Biometry Measurement Area 30 m 90 m N Biometry Measurements Biometry Measurement Area – Pacing Semi-Diagonals NE NW N 30 m 21.2 m canopy cover ground cover SW 30 m SE Density of Vegetation Cover Homemade Tube Densiometer – Two diagonal transects – Measurements of green vegetation ‘hits’ intersecting tube’s ‘crosshair’ at each ‘pace’ along transect – % Tree Cover = 100 X ‘Trees’/total number of measurements Sky ‘+’ = tree or shrub 6 Biometry Measurements Biometry Measurement Area – Pacing Semi-Diagonals NE NW 30 m N SW 30 m SE Biometry Measurements From pacing semi-diagonals can determine: 1) Tree Canopy Cover Percentage 2) Shrub Cover Percentage 3) Identity of Dominant and Co-Dominant Species Still need: 4) Tree Heights of Dominant Species and Co-Dominant Species 5) Tree Circumferences of Dominant Species and Co-Dominant Species Biometry Measurements Measuring Tree Height Using right-angle trigonometric relationships h Angle eye Distance height Tan(Angle) = h / Distance h = Distance * Tan(Angle) Height = h + eye height Height = Distance * Tan(Angle) + eye height Height Tree Height Clinometer: Alternative techniques: Advanced trigonometric methods for non-level ground - Simplified version involving 45 degree angle - Biometry Measurements What you need in the field: – – – – – – – – – – GPS Compass(es) MUC, and local vegetation student field guides Camera Tubular densiometer(s) Clinometer(s) 50m tape measure(s) Flags Knowledge of your pace length Land Cover Sample Site and Biometry Data Sheets Grassland Measurements a. Three or more locations are chosen at random. b. A one-meter square is marked at each location. Grassland Measurements All grasses within the one meter square are clipped as close to the soil as possible. Grassland Measurements a. Use grass clippers or strong scissors. b. Collect all grasses. c. Discard leaves, twigs, other non-grass materials. Grassland Measurements At School: Samples are divided into green (living) and brown (senescent). Samples are placed in brown bags (NOT PLASTIC) for drying. Grassland Measurements Samples are dried at 50 -70 degrees Celsius. DO NOT use a conventional oven. Bags are weighed ~ daily until no weight change is seen from day-to-day.